Évaluation du risque transfusionnel vis-à-vis de la variante de la maladie de Creutzfeldt-Jakob en France

Notification and support for people exposed to the risk of Creutzfeldt-Jakob disease (CJD) (or other prion diseases) through medical treatment (iatrogenically)

BACKGROUND

Creutzfeldt-Jakob disease (CJD) and variant CJD (vCJD) are rare and always-fatal diseases transmissible via certain medical procedures. If a person is exposed to the disease risk through medical treatment, they may need to be notified of this to prevent them passing the risk to others in healthcare settings and to enable additional infection control measures to be put in place for certain procedures. As CJD is incurable, and unable to be screened for or effectively treated, communicating this risk information after an exposure incident may have significant implications for the person at risk, their families/ carers and healthcare professionals. The best ways to notify people of their exposure to the risk of CJD or vCJD, and to support them subsequently, are currently unknown.

OBJECTIVES

To evaluate the effects of interventions to notify and support consumers (patients and their family members or carers) in situations where exposure to the risk of CJD or vCJD has occurred as a result of medical treatment (iatrogenically), on consumer, healthcare provider and healthcare system outcomes.

SEARCH STRATEGY

We searched the Cochrane Consumers and Communication Review Group Specialised Register (10 February, 2009), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1 2009), MEDLINE (OVID SP), EMBASE (OVID SP), PsycINFO (OVID SP), CINAHL (EBSCO Host), Current Contents (OVID SP) and Dissertation Abstracts (Proquest) from start date to February 2009. We searched MEDLINE In-process and Other Non-indexed Citations (OVID SP) and Sociological Abstracts (CSA) in November 2009. We searched reference lists, websites, and contacted consumer groups and experts for details of relevant research.

SELECTION CRITERIA

Randomised and quasi-randomised controlled studies, controlled before-and-after studies and interrupted time series analyses assessing the effects of any intervention to communicate with (notify or support) people exposed to the risk of CJD or vCJD through medical treatment were included. We sought outcomes relevant to consumers, health providers and health services, including both benefits and harms.

DATA COLLECTION AND ANALYSIS

Cochrane reviewTwo authors independently assessed studies for inclusion against selection criteria, and would have applied standard Cochrane review methodology were any studies identified.Thematic synthesisWe also conducted a thematic synthesis by systematically identifying and screening those studies that met the same population, intervention and outcome criteria as the Cochrane review, but that were identified from the broader literature providing evidence on policy implementation and consumer experiences. We systematically extracted and synthesised the data from these studies to produce a thematic synthesis, presented in appendices to this Cochrane review, which assembles evidence on the views, experiences and acceptability of notification and support strategies for people at risk.

MAIN RESULTS

Results of the Cochrane reviewNo studies meeting the study design criteria were identified for inclusion in this Cochrane review.Results of thematic synthesisIn total, 49 studies and pieces of literature meeting the same population, intervention and outcome criteria as the Cochrane review, but identified from the broader literature providing evidence on policy implementation and consumer experiences, were included and formed the basis of a thematic synthesis, and which is presented in appendices to this Cochrane review. The thematic synthesis indicates that ideally communication may be considered as a longitudinal multicomponent programme, ensuring that notification and support are coordinated; that communication is tailored and responsive to need; and that activities to support individual risk communication, such as widespread education and monitoring of access to health care for those at risk, are in place. The thematic synthesis also indicates that poor communication practices may have negative impacts or cause harm, such as discrimination in accessing health care.

AUTHORS' CONCLUSIONS

There is insufficient rigorous evidence to determine the effects of interventions to notify people at CJD or vCJD risk and to support them subsequently, or to identify the best approach to communication in these situations. The thematic synthesis can be used to inform policy and practice decisions for communicating with people at risk in the absence of rigorous evaluative studies.

From mad cows to sensible blood transfusion: the risk of prion transmission by labile blood components in the United Kingdom and in France

Transfusion transmission of the prion, the agent of variant Creutzfeldt-Jakob disease (vCJD), is now established. Subjects infected through food may transmit the disease through blood donations. The two nations most affected to date by this threat are the United Kingdom (UK) and France. The first transfusion cases have been observed in the UK over the past 5 years. In France, a few individuals who developed vCJD had a history of blood donation, leading to a risk of transmission to recipients, some of whom could be incubating the disease. In the absence of a large-scale screening test, it is impossible to establish the prevalence of infection in the blood donor population and transfused patients. This lack of a test also prevents specific screening of blood donations. Thus, prevention of transfusion transmission essentially relies at present on deferral of "at-risk" individuals. Because prions are present in both white blood cells and plasma, leukoreduction is probably insufficient to totally eliminate the transfusion risk. In the absence of a screening test for blood donations, recently developed prion-specific filters could be a solution. Furthermore, while the dietary spread of vCJD seems efficiently controlled, uncertainty remains as to the extent of the spread of prions through blood transfusion and other secondary routes.

[The risk of prion contamination through the transfusion of cellular products]

Since the publication of observations of variant Creutzfeld-Jacob disease (vCJD) having occurred in the UK due to transfusion of infected packed red cells, the risk of vCJD transmission by blood transfusion is established. In France, no such case has yet been reported, but among the French vCJD cases observed, three individuals, having entered the disease in 2004, are past blood donors. Thus, some individuals transfused in their past are at risk of developing a vCJD. The lack of available assay prevents the diagnosis of the infection in these recipients and the implementation of a specific screening of blood donations. In the UK and in France, several measures to ensure transfusion safety have been applied to reduce the risk of contamination by the variant.